The Transport of Charged Particles in a Flowing Medium
Bibliographic record
Abstract
The propagating source method for solving the time-dependent Boltzmann equation describing particle propagation in a magnetically turbulent medium is extended to a more realistic case that includes focusing and adiabatic deceleration. The solutions correspond to beam propagation in the solar wind. Pitch-angle scattering away from 90° is described by standard quasi-linear theory (QLT), while scattering through 90° is approximated by a BGK operator representing a slow mirroring process. The detailed numerical technique for solving the Fokker-Planck equation for two particular spectra is presented. Comparisons are made between our modified QLT (MQLT) model and a BGK model, between highly anisotropic scattering and moderately anisotropic scattering, and between fast particles and slow particles. It is shown that: (1) for moderately anisotropic pitch-angle scattering, the initial ring-beam distribution finally evolves into a broad Gaussian distribution and the QLT isotropic and MQLT anisotropic models could be rather well approximated by the simple relaxation time operator. (2) For highly anisotropic pitch-angle scattering, a moving pulse with a spatially extended flat tail is formed, and there exist some differences between the MQLT and BGK models. Specifically, at a particular pitch angle, the spatial distribution from MQLT model occupies a much wider region than that in the BGK model. (3) In the highly anisotropic scattering medium, more particles are cooled by adiabatic deceleration, some particles move a little faster, and the spatial distribution at a specific pitch angle is much more dispersed than that in the case of moderately anisotropic scattering. (4) Compared with the BGK model, the anisotropy persists for a little longer and some particles move a little slower; consequently, intensity profiles have a greater amplitude at later times in the MQLT model. (5) Finally, fast and slow particles have similar distribution characteristics, except that convection is much more important for slow particles.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".